Extension ring for a convection oven



FIG. 1 is a perspective view of an extension ring for a convection oven showing our new design, the convection oven shown in broken lines is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for a extension ring for a convection oven, as shown and described. 